The present invention relates to a method for repairing pipe line leaks and more particularly to a method of repairing and sealing leaking flange pipe couplings and the like.
Flange pipe couplings are widely used for connecting various sections of pipe which operate in moderate to high pressures. Various configurations of seals are utilized between the flanges. One of the most common configurations is a raised face on the inner portion of each of the flanges with an annular gasket being placed between the raised faces. When the flanges are bolted together, the raised flanges compress the gasket material to form a seal. Leaks often begin in such flange pipe couplings because of deterioration of the gasket material or by shifting of the pipe.
Similarly, a leak may occur in the outer wall of a pipe section due to a defect in the manufacture of the pipe because of damage done to the pipe during or after installation. Such leaks must be repaired and, often in the past, the pipeline had to be shut down and drained of its contents before the repair could be affected.
As a result of the problem of repairing these pipe flanges, a number of techniques for sealing a leak between pipe flanges have been known in the prior art. Flange gasket leaks have been repaired by flange enclosures which completely enclose the flange which enclosure is filled with a hardening plastic or material to completely seal the flange joint when the plastic hardens. A wire wrap repair uses wires clamped over the edges of the flanges or use flat face band for flange repairs. Other flange repairs have been accomplished with a crunch-groove clamp or tongue clamp repair or with a tongue and packing clamp repair. It has also been suggested to use a packing clamp tubing repair, a full packing clamp repair and a flange-to-line clamp.
One prior U.S. patent which relates to a method and apparatus for sealing a leak in a pipeline can be seen in U.S. Pat. No. 4,209,029 for a method and apparatus for sealing a leak in a pipeline in which a leak repair clamp is provided for originally sealing the leak. The clamp includes a body forming a cavity between the pipeline and body for receiving a sealant in the passageway through the body for injecting the sealant in the cavity. A plug is provided for stopping the sealant passageway after the sealant has been injected. U.S. Pat. No. 4,607,469 provides a seal for waterproofing a utility line, conduit and a method of forming the seal. U.S. Pat. No. 4,576,401 is a leak repair clamp for pipe and pipe flanges which includes a frame having a plurality of one piece frame segments positionable in end-to-end relationship around the pipe. Access is provided to each frame segment to permit the passing of liquid sealant into the recess defined by the segment. U.S. Pat. No. 4,568,091 is for a leak repair clamp with a flexible lip seal that allows a sleeve to be fitted around the outside of a cylindrical surface and an elastomeric fluid pressure seal segment mounted within each groove in the sleeve to provide a fluid-type seal within the space confined between the grooves. In U.S. Pat. No. 4,202,377, a pipe cleaning and plugging apparatus allows plugging a pipeline through a side opening while U.S. Pat. No. 4,133,351 is a method and apparatus for sealing a pipeline leak which occurs at the flanged connection of pipelines using a wire wrapped around the upper surface of the flange connecting bolts for filling the gap between the flanges and above the bolts. An injection valve means is installed for relieving pressure from inside the gas while the wire is being wrapped and for injecting a sealant to the interior of the gap between the wire wrap. A sealant is used to fill the gap between the wire wrap for stopping the leak. In U.S. Pat. No. 4,268,070, an orifice flange clamp has a pair of semi-circular bands adapted to be clamped together around the periphery of the inner face of orifice flanges. U.S. Pat. No. 4,108,194 is a method and apparatus for a tapered pipeline seal and includes means for enabling a line to be sealed with a rotatable tapered sealing plug.
One of the problems with prior art methods for sealing flange gasket leaks is that the pipes are leaking after the flange joints have been enclosed and while the sealant is being injected into the casing and before the sealant hardens. This allows puddling or weakened areas in the sealant while the sealant is curing which thereby reduces the strength of the flange joint seals. The present invention is directed towards an improved method of repairing flange pipe joints which allows a leaking seal on a flange joint to continue leaking and to be drained away until the repair has been completely affected after the seal encasing material, such as an epoxy sealant, has completely encapsulated the flange joint except for a drainage opening. The drainage opening can then be sealed to complete the repair. This makes for a fast repair in which a sealing bladder of flexible material, such as a flexible plastic sheet, has a tube attached therethrough with an end shaped to fit against the flange joint of a leaking pipe. The bladder sheet can then enclose the flange joint and be strapped to the leaking flange joint. A coating, such as an epoxy, can then be coated over the entire bladder on the outside to seal the entire bladder and adjacent pipe within an encapsulating material which is allowed to cure in the open air without any contact from liquid leaking from a flange seal. Once the repair has been completed, the drainage tube is plugged or sealed off.
It is accordingly an aim of the present invention to provide an improved method of sealing a pipe flanged joint to seal flange gasket leaks which obviates the problem of the sealing material becoming weakened or contaminated by a leaking fluid.